Conventional vertical window blinds have vertical slats on louvers suspended from a head rail that can be mounted at the top of a window so that the slats extend down to the bottom of the window. By turning a wand, the slats can be rotated in unison about their vertical axes between a closed position wherein the slats lie almost parallel to the window essentially forming a single panel which blocks the light and an open position wherein the slats are oriented at right angles to the window, thus allowing a maximum amount of light to pass through the blind. The slats can also be set at any angle between those two extremes. However, even when slats of the prior blinds are in their fully open position, they still occlude the window to some extent in that an observer sees the edges of the slats when looking out the window.
Some vertical blinds are also disadvantaged in that they are usually fabricated in relatively few widths to fit standard window sizes. Therefore, they may not be suitable for windows that do not conform to those standards.